The present invention relates to liquid crystal display apparatus, particularly, to active matrix liquid crystal display apparatus and IC (Integrated Circuit) cards.
Currently, active matrix liquid crystal display apparatus using active elements represented by TFT (Thin Film Transistor) have been widely used as monitors for personal computers and work stations, in view of their high image quality as same as CRT (Cathode Ray Tube), low consuming power less than CRT, and saving space. However, the active matrix liquid crystal display apparatus is expensive in comparison with the CRT, and lowering its price further is required in order to be used wider.
As one of methods for lowering its price, application of organic thin film transistor (organic TFT), which can be manufactured readily, to the active element is proposed. Plasma Chemical Vapor Deposition (CVD) apparatus for manufacturing insulating layers and semiconductor layers of the current amorphous silicone TFT, and spattering apparatus for manufacturing electrodes are significantly expensive. Furthermore, the CVD method requires a high temperature in the range of 230-350.degree. C. for forming films, and throughput of the apparatus is low, because the apparatus requires frequent maintenance such as cleaning and the like. On the other hand, application apparatus and vapor deposition apparatus for manufacturing the organic TFT is cheap in comparison with the CVD apparatus and the spattering apparatus. The temperature for forming films using the above apparatus is lower, and their maintenance is easier in comparison with the CVD apparatus and the spattering apparatus. Therefore, significant decrease in production cost can be realized by applying the organic TFT for the liquid crystal display apparatus.
Generally, an organic TFT is composed of a glass substrate, gate electrodes, gate insulating film, source electrodes, drain electrodes, and organic semiconductor film. Charging amount at a boundary between the gate insulating film and the organic semiconductor can be altered from excessive to deficient, or vice versa, by varying the voltage applied to the gate electrode. Switching is performed by varying a drain current value flown through the source electrode/the organic semiconductor/the drain electrode.
A method for manufacturing the organic TFT using sexithiophene oligomer vapor deposition film as the organic semiconductor film was disclosed in JP-A-8-228035 (1996). In accordance with a reference (Y-Y, Lin, D. J. Gundlach, S. F. Nelson, and T. N. Jackson; IEEE Transactions on Electron Devices, Vol. 44, No. 8, p 1325-1331 (1997)), a method for manufacturing a high performance organic TFT using pentacene vapor deposition film as the organic semiconductor film was disclosed. JP-A-8-191162 (1996) disclosed a method for manufacturing an organic TFT using organic materials for semiconductor film, source electrodes, drain electrodes, and gate electrodes, wherein the gate insulating film is made of an insulating polymer having cyano-groups.
In accordance with JP-A-8-228035 (1996) and JP-A-10-125924 (1998), the organic semiconductor films were formed by vapor deposition methods, but pattern formation of the semiconductor was not described. For instance, when the pattern is formed using a metallic mask made of molybdenum, the minimum size of the pattern becomes approximately 100 .mu.m, which is larger than a pixel size (10.times.30 .mu.m.sup.2) in the current liquid crystal display apparatus. When conventional lithography (photolithography) is used, deterioration by carrier injection into the semiconductor layer and the like in an annealing process for removing a polar solvent or a solvent used for resist materials is concerned. Two terminal electron element having the organic semiconductor layer, wherein a pattern was formed between two parallel electrodes on a substrate, was disclosed in JP-A-2-239663 (1990). In accordance with JP-A-2-239663 (1990), a patterned insulating film, wherein electrodes portion were removed, was formed on a lower electrode, and an organic semiconductor film having the same size as the lower electrode was formed using the lower electrode. However, the material was restricted to an organic material which would be an electron donor such as tetracyanoquinonedimethane and the like, and other materials can not be used. Furthermore, the invention can not be applied to three terminal elements such as TFT and the like.